The present invention relates generally to missile launchers, and more particularly, to an improved launcher attachment bolt locking assembly for use with missile launchers.
To prevent a bolt or nut from loosening during vibration one of the following methods is typically used.
A locking element, such as a Ny-Lock or Vespel type locking element, for example, is placed in threads of the bolt or nut to provide resistance from loosening. The disadvantages of this type of locking element are that it is only good for 10-15 installations and removals, and there is no positive indication that such locking elements are functioning.
A sealant such as Locktite sealant, for example, is placed on the threads prior to assembly to prevent loosening. The disadvantages using sealant is that when the bolt or nut is replaced, the threads must be resealed during each installation.
A mechanical lock, such as a lockwire or a cotter pin, for example, is placed through a hole in the bolt or nut, or in some cases through both the bolt and the nut to mechanically lock them to prevent rotation. The disadvantage to using mechanical locking elements is the time and effort required to remove the lockwire or cotter pin before removal of the bolt or nut. The lockwire or cotter pin also must be reinstalled when the bolt or nut is reinstalled.
None of the above conventional techniques provide both a visually verifiable mechanical lock and the ease of frequent installation and removal of the nut or bolt. Furthermore, the operating life of the currently used locking element is too short and there is no indication or means to verify when this locking element is worn out.
With specific regard to missile launcher applications, AMRAAM LAU-129 launchers and other similar launchers manufactured by the assignee of the present invention use attachment bolts and locking elements that are inserted into threaded holes. A pre-load torque is applied to the bolts to prevent the bolts from loosening during flight. The material from which the conventional locking elements are made is typically a heavy-duty nylon plastic material (such as those made by Ny-Lock or Vespel, for example). The conventional locking elements must be replaced after 10-15 installations. A user does not have a way to monitor the number of installations any one bolt has seen, and as a result, bolts with bad locking elements may be used.
Accordingly, it is an objective of the present invention to provide for an improved attachment bolt locking assembly. It is a further objective of the present invention to provide for an improved attachment bolt locking assembly that may be used with missile launchers, and other devices that experience vibration.